Washing machine and method for controlling the same

ABSTRACT

A washing machine having a plurality of washing units and a method for controlling the same are disclosed. The washing machine classifies overall laundry according to the capacity or categories of laundry and independently washes the classified laundry using different washing units. The washing machine includes several washing units capable of classifying laundry according to the capacity or categories of laundry so as to separately wash the classified laundry in different washing ways, so that a user need not manually separate the laundry and the washing machine is not required to be driven several times, thereby reducing an overall washing time and implementing energy saving measures. If several washing units are simultaneously driven, the washing machine according to an embodiment monitors vibrations of the several washing units using a vibration sensor, so that excessive or abnormal vibrations of the washing machine can be effectively reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2015-0013366, filed on Jan. 28, 2015 in the Korean Intellectual Property Office and U.S. Provisional Application Ser. No. 62/108,304, filed on Jan. 27, 2015, the contents of which are hereby incorporated by reference in their entirety.

BACKGROUND

1. Field

Embodiments of the present invention relate to a washing machine having a plurality of washing units and a method for controlling the same, and more particularly to a washing machine configured to reduce vibration generated from the plurality of washing units and a method for controlling the same.

2. Description of the Related Art

Generally, a washing machine includes a tub accommodating water (e.g., washing water or rinsing water) therein, a drum rotatably installed in the tub to accommodate laundry therein, and a motor configured to generate driving force to rotate the drum, so that the washing machine can wash dirty laundry using the water and detergent.

A washing machine performs washing of laundry through a series of operations such as a washing process of separating contaminants from laundry with water in which detergent is dissolved (for example, wash water), a rinsing process of rinsing bubbles and/or residual detergent within the laundry with water without the detergent (for example, rinse water), and a dehydrating process of dehydrating the laundry at high speed.

In recent times, the washing machine is configured to have a drying function, so that the washing machine can also perform a drying process of drying the dehydrated laundry.

However, it may be impossible for the washing machine to simultaneously wash a plurality of laundries accommodated in one drum according to categories or materials of laundry. If the washing machine has one drum, the user must directly classify a plurality of laundries into various types of laundries before execution of the washing machine, and select only some laundries incapable of being simultaneously washed in one drum from among total laundries, so that the user must allow the washing machine to separately wash only the selected laundries through an additional washing process after washing completion of the remaining laundries. In this case, the user may feel inconvenienced because the user must select some laundries to be washed in a separate washing process from among total laundries and the washing machine must be driven several times (e.g., twice), resulting in a waste of energy and time. In addition, although the user desires to wash a small amount of laundries using a washing machine, if a drum of the washing machine is a large-capacity drum, unnecessary power consumption occurs.

SUMMARY

Therefore, it is an aspect of the present invention to provide a washing machine having a plurality of washing units, configured to classify overall laundries according to the capacity or categories of laundries and independently wash the classified laundries using different washing units, and a method for controlling the same.

It is another aspect of the present invention to provide a washing machine having a plurality of washing units, configured to persistently monitor vibrations generated between the plurality of washing units using a vibration sensor so as to greatly reduce the number of vibrations, and a method for controlling the same.

Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

In accordance with an aspect of the present invention, a washing machine includes a plurality of washing units, a vibration sensor configured to detect vibrations of the plurality of washing units, and a controller, while the plurality of washing units is in a dehydration process, configured to control the dehydration process of any one of the plurality of washing units according to data of the vibrations detected by the vibration sensor.

The washing machine may further include a plurality of tubs installed in the plurality of washing units, respectively, a plurality of drums rotatably installed in the plurality of tubs, respectively, and a plurality of motors configured to respectively rotate the plurality of drums, wherein the controller controls any one of the plurality of motors using the data detected by the vibration sensor.

The controller may compare data detected by the vibration sensor with predetermined excessive vibration data, and delay dehydration entering of any one of the plurality of motors when the detected data is equal to or higher than the predetermined excessive vibration data, resulting in reduction of vibrations of the washing machine.

The excessive vibration may occur in an entry section of the dehydration process.

The controller may compare data detected by the vibration sensor with predetermined normal vibration data, and control a dehydration rpm of any one of the plurality of motors when the detected data is equal to or higher than the normal vibration data, resulting in reduction of vibrations of the washing machine.

The controller may compare data detected by the vibration sensor with abnormal vibration data, and stop any one of the plurality of motors when the detected data is equal to or higher than the abnormal vibration data, resulting in reduction of vibrations of the washing machine.

The abnormal vibration may occur in a normal progressing section of the dehydration process.

The plurality of washing units includes: a first washing unit in which a first tub and a first drum are arranged, configured to form a first inlet at an upper part thereof so as to withdraw laundry; and a second washing unit in which a second tub and a second drum are arranged, configured to form a second inlet at a front surface thereof so as to withdraw laundry.

The vibration sensor may be configured to detect vibrations generated between the first washing unit and the second washing unit when the plurality of motors is simultaneously rotated at a high speed.

The vibration sensor may be installed between the first washing unit and the second washing unit, measure displacement of the first and second tubs moving in response to vibrations of the first and second drums, and transmit the measured displacement to the controller.

The washing machine may further include: a vibration reduction unit installed between the first washing unit and the second washing unit, configured to include at least one elastic unit so as to reduce vibrations.

The vibration sensor may be mounted to the vibration reduction unit.

The plurality of washing units may include: a first washing unit and a second washing unit vertically stacked to be operated independently of each other.

The first washing unit and the second washing unit may have different capacities.

The first washing unit and the second washing unit may be comprised of a drum washing machine or a fully automatic washing machine.

In accordance with another aspect of the present invention, a washing machine includes a plurality of washing units configured to form an external appearance of the washing machine; a plurality of tubs installed in the plurality of washing units, respectively, a plurality of drums rotatably installed in the plurality of tubs, respectively, a plurality of motors configured to respectively rotate the plurality of drums, a vibration sensor configured to detect vibrations of the plurality of tubs during rotation of the plurality of drums, and a controller configured to control any one of the plurality of motors according to data of the vibrations detected by the vibration sensor so as to reduce vibrations.

The vibration sensor may be installed between the first washing unit and the second washing unit, detect vibrations generated between the first washing unit and the second washing unit when the plurality of motors is simultaneously rotated at a high speed.

In accordance with another aspect of the present invention, a method for controlling a washing machine having a plurality of washing units includes determining whether the plurality of washing units are in a dehydration process, and while the plurality of washing units are determined to be in the dehydration process, detecting vibrations of the plurality of washing units using a vibration sensor, and controlling the dehydration process of any one of the plurality of washing units according to data of the detected vibrations.

The determining the plurality of washing units in a dehydration process may include: if the detected data is equal to or higher than reference data, determining that the plurality of washing units simultaneously perform the dehydration process.

The controlling the dehydration process of any one of the plurality of washing units may include: controlling any one of the plurality of motors configured to rotate the plurality of drums respectively installed in the plurality of washing units, and thus reducing vibrations of the washing machine.

The method may further include: comparing the data detected by the vibration sensor with excessive vibration data; and if the detected data is equal to or higher than the excessive vibration data, delaying dehydration entering of any one of the plurality of motors when the detected data is equal to or higher than the excessive vibration data, and thus reducing vibrations of the washing machine.

The method may further include: comparing the data detected by the vibration sensor with normal vibration data; and if the detected data is equal to or higher than the normal vibration data, controlling a dehydration rpm of any one of the plurality of motors, and thus reducing vibrations of the washing machine.

The method may further include: comparing the data detected by the vibration sensor with abnormal vibration data; stopping operation of any one of the plurality of motors when the detected data is equal to or higher than the abnormal vibration data, and thus reducing vibrations of the washing machine.

The detecting of vibrations generated between the plurality of washing units may include: detecting, by a vibration sensor disposed between the plurality of washing units, vibrations of the washing machine during rotation of the plurality of drums.

The detecting of vibrations generated between the plurality of washing units may include: detecting, by a vibration sensor disposed between the plurality of washing units, vibrations generated between the plurality of washing units during high-speed rotation of the plurality of motors.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a first perspective view illustrating the external appearance of a washing machine according to an embodiment of the present invention.

FIG. 2 is a second perspective view illustrating the external appearance of a washing machine according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a structure of a washing machine according to an embodiment of the present invention.

FIG. 4 is a configuration view illustrating a vibration reduction unit of a washing machine according to an embodiment of the present invention.

FIG. 5 is a block diagram illustrating a washing machine according to an embodiment of the present invention.

FIG. 6A and FIG. 6B are a flowchart illustrating a control algorithm of a washing machine according to an embodiment of the present invention.

FIG. 7 is a conceptual diagram illustrating a dehydration process profile of a washing machine according to an embodiment of the present invention.

FIG. 8 is a graph illustrating a rotation speed of a washing motor and a vibration range of a tub for use in a washing machine according to an embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

FIG. 1 is a first perspective view illustrating the external appearance of a washing machine according to an embodiment of the present invention. FIG. 2 is a second perspective view illustrating the external appearance of a washing machine according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a structure of a washing machine according to an embodiment of the present invention.

Referring to FIGS. 1 to 3, a washing machine 100 according to an embodiment includes a plurality of washing units (e.g., at least 2 washing units) 110 and 210 capable of being driven independently of each other or being interconnected and driven. The washing units 110 and 210 have a stacked structure of an upper washing unit and a lower washing unit, so that a first washing unit 110 serving as a fully automatic washing machine is installed as the upper washing unit and a second washing unit 210 serving as a drum washing machine is installed as the lower washing unit. In accordance with the washing machine 100 including a plurality of washing units 110 and 210, the first washing unit 110 may be stacked on the top surface (not shown) of the second washing unit 210. A user may separately purchase the first washing unit 110 and the second washing unit 210 so that the user may use the first and second washing units 110 and 210 as different washing machines. If necessary, the user may simultaneously or separately purchase the first washing unit 110 and the second washing unit 210, and the first washing unit 110 may be stacked on the top surface of the second washing unit 210.

Although the first washing unit 110 and the second washing unit 210 may be composed of the same-capacity washing units for convenience of description, the first washing unit 110 and the second washing unit 210 are preferably classified into a large-capacity washing machine and a small-capacity washing machine because the washing machine 100 has several washing units 110 and 210.

Meanwhile, although the embodiment has exemplarily disclosed that the first washing unit 110 installed at an upper part is used as the fully automatic washing machine and the second washing unit 210 installed at a lower part is used as a drum washing machine for convenience of description and better understanding of the present invention, the scope or spirit of the present invention is not limited thereto, and it should be noted that each of the first washing unit 110 and the second washing unit 210 can be used as a fully automatic washing machine or a drum washing machine as necessary.

In addition, although the embodiment has exemplarily disclosed that the first washing unit 110 and the second washing unit 210 are respectively stacked as the upper washing unit and the lower washing unit for convenience of description, the scope or spirit of the present invention is not limited thereto, and it should be noted that the first washing unit 110 and the second washing unit 210 may be installed as a left washing unit and a right washing unit in a parallel manner as necessary.

The first washing unit 110 includes a first tub 120 installed therein to accommodate water (e.g., wash water or rinse water), and a first drum 130 rotatably installed in the first tub 120 to accommodate laundry.

The second washing unit 210 includes a second tub 220 installed therein to accommodate water, and a second drum 230 rotatably installed in the second tub 220 to accommodate laundry.

The first washing unit 110 is smaller in capacity (volume) than the second washing unit 210, so that the first tub 120 and the first drum 130 installed in the first washing unit 110 are smaller in capacity (volume) than the second tub 220 and the second drum 230.

If only one drum is installed in the washing machine 100, laundry is put into one drum irrespective of the amount of laundry and then washed in the drum. As a result, a small amount of laundry should be unavoidably washed in the large-capacity (volume) drum, resulting in unnecessary power consumption. However, the first drum 130 and the second drum 230 installed in the washing machine 100 are respectively installed in the first washing unit 110 and the second washing unit 210. If there is a large amount of laundry, the large amount of laundry is put into the second drum 230 installed in the second washing unit 210 having large capacity (volume) and then washed. If there is a small amount of laundry, the small amount of laundry is put into the first drum 130 installed in the first washing unit 110 having small capacity (volume) and then washed.

As described above, if the user desires to wash a small amount of laundry, only the small-capacity first washing unit 110 is driven so that unnecessary power consumption can be prevented. A first inlet 111 through which laundry is input to the inside of the first drum 130 is installed above the first washing unit 110, and may be opened or closed by a first door 113. The first door 113 may include a first inner door 113 a and a first outer door 113 b configured to open or close the first inlet 111.

A first control panel 115 including a display and various buttons needed to control the first washing unit 110 is provided at a front lower portion of the first washing unit 110.

The first control panel 115 may include various buttons 115 a configured to receive a user command needed to control the first washing unit 110, and a first display unit 115 b configured to display an operation state of the first washing unit 110 and a manipulation state of the user.

The first tub 120 is provided to accommodate water therein, and is installed in the first washing unit 110 so that the first tub 120 is supported by the first washing unit 110 through a damper 121.

The first drum 130 is formed in a cylindrical shape having an opened top portion, and is rotatably installed in the first tub 120.

A plurality of through-holes 131 through which water flows into or out of the first drum 130 may be formed at a lateral surface of the first drum 130. A balancer 133 may be formed at an upper portion of the first drum 130 so that the first drum 130 can stably rotate during high-speed rotation of the first drum 130.

A pulsator 135 may be rotatably installed at the bottom of the first drum 130, and the pulsator 135 may agitate laundry placed in the first drum 130 along with wash water.

A flange shaft 137 is coupled to a lower portion of the first drum 130 and coupled to a rotation shaft 161, so that the first drum 130 rotates by the first washing motor 150.

A first washing motor 150 is installed at a lower portion of the first tub 120. The first washing motor 150 may generate driving force to rotate the pulsator 135 and the first drum 130. The first washing motor 150 is coupled to a power switching unit 160 configured to simultaneously or selectively transmit the driving force generated from the first washing motor 150 to the first drum 130 and/or the pulsator 135.

The first washing motor 150 may be a direct drive (DD) motor having a variable speed function. The first washing motor 150 may selectively transmit the driving force to the first drum 130 or the pulsator 135 according to the ascending or descending operation of the power switching unit 160.

A universal motor including a field coil and an armature, a brushless direct current motor (BLDC) motor including a stator and a rotor may be employed as the first washing motor 150, and any motor applicable to the washing machine 100 may be allowed as the first washing motor 150. In addition, the first washing motor 150 may also be configured in a belt type.

A first drain hole 170 is formed on the bottom of the first tub 120 to drain water from the first tub 120 to the outside, and a first drainpipe 171 configured to drain water to the outside is connected to the first drain hole 170. A drain motor 173 is installed in the first drainpipe 171 to control drainage.

Although the above-mentioned embodiment has exemplarily disclosed that the drain motor 173 is installed to drain water, the scope or spirit of the present invention is not limited thereto, it should be noted that a drain pump or a drain valve may also be installed in the washing machine of the above-mentioned embodiment.

A detergent supply unit 140 and a water supply unit 180 are installed at an upper top surface of the first washing unit 110. The detergent supply unit 140 may supply the detergent and fabric conditioner into the first tub 120 and the second tub 220. The water supply unit 180 may supply water to the first tub 120 and the second tub 220.

The detergent and fabric conditioner contained in the detergent supply unit 140 may pass through the detergent supply unit 140, and then be supplied to the first tub 120 and the second tub 220 by the water supply unit 180 connected to the first tub 120 and the second tub 220.

The water supply unit 180 includes: a water supply pipe 181 configured to interconnect an external water supply pipe and the detergent supply unit 140 so as to supply water (e.g., wash water and rinse water) into the first tub 120 and the second tub 220; and a water supply valve 182 installed at an intermediate portion of the water supply 181 to control supply of hot water and cool water. The above-mentioned configuration may allow water supplied into the first tub 120 and the second tub 220 to pass through the detergent supply unit 140 so that the detergent can be supplied to the first tub 120 and the second tub 220 along with water.

A second inlet 211 through which laundry is input to the inside of the second drum 230 is installed at the front center portion of the second washing unit 210, and is opened or closed by a second door 213 installed at a front portion of the second washing unit 210. The second door 213 may include a second inner door 213 a and a second outer door 213 b configured to open or close the second inlet 211.

A second control panel 215 including a display and various buttons needed to control the second washing unit 210 is provided at a front upper portion of the second washing unit 210.

The second control panel 215 may include various buttons 215 a configured to receive user commands needed to control the second washing unit 210, and a second display unit 215 b configured to display an operation state of the second washing unit 210 and a manipulation state of the user.

Meanwhile, although the embodiment has exemplarily disclosed that the first control panel 115 of the first washing unit 110 and the second control panel 215 of the second washing unit 210 are configured separately from each other for convenience of description, the scope or spirit of the present invention is not limited thereto, and the first control panel 115 and the second control panel 215 can be integrated into one control panel so that the first washing unit 110 and the second washing unit 210 can be simultaneously controlled using the integrated control panel without departing from the scope or spirit of the present invention.

Water to be used for washing is stored in the second tub 220, and the second tub 220 is supported by the damper 225. The damper 225 may connect the inner bottom surface of the second washing unit 210 to the outer surface of the second tub 220, and may reduce vibration generated from the bottom portion of the second tub 220.

A bearing housing 221 capable of rotatably supporting the rotation shaft 255 connected to the second washing motor 250 is insert-molded at a rear wall of the second tub 220. Bearings 223 rotatably supporting the rotation shaft 255 are installed in the bearing housing 221.

The second drum 230 may include a main body 231 having a cylindrical shape, a front plate 233 installed at a front side of the main body 231, and a rear plate 235 installed at a rear side of the main body 231. A plurality of through holes 231 a through which water passes may be formed around the second drum 230, and several lifters 231 d are installed at the inner circumferential surface of the second drum 230 so that laundry rises during rotation of the second drum 230. Here, the plurality of lifters 231 d may be spaced apart from each other at intervals of a predetermined distance in the circumferential direction.

An opening 233 a through which laundry is put into the drum is formed at the front plate 233, and a shaft flange 235 a coupled to the rotating shaft 255 of the second washing motor 250 may be installed at the rear plate 235.

A detergent box 240 configured to supply the detergent and bleach into the second tub 220 is installed at an inner upper portion of the second washing unit 210, and the detergent and bleach of the detergent box 240 may pass through the detergent box 240 so that the detergent and bleach along with water is then supplied into the second tub 220 by the water supply unit 180 connected to the second tub 220.

The second washing motor 250 may include a stator 251 fixed to a rear surface of the second tub 220, a rotor 253 configured to rotate while interacting with the stator 251, and a rotation shaft 255, one end of which is fixed to a center of the rotor 253 while the other end thereof passes through the second tub 220 and is fixed to a center of the rear plate 235 of the second drum 230.

The rotation shaft 255 rotates by the rotor 253 which rotates while interacting with the stator 251, and the second drum 230 connected to the rotation shift 255 rotates by rotation of the rotation shaft 255 so that laundry can be washed.

The second washing motor 250 is typically a universal motor configured by a field coil and an armature or a BLDC (Brushless Direct Current) motor configured by a permanent magnet and an electromagnet. Furthermore, any motor may also be utilized as long as the second washing motor 250 is applicable to the washing machine 100.

A drain unit 270 configured to drain water used in laundry washing to the outside of the second washing unit 210 is installed at a lower portion of the second tub 220.

The drain unit 270 may include a second drainpipe 271 allowing water of the second tub 220 to be drained to the outside of the second washing unit 210, and a drain pump 273 installed in the second drainpipe 271 so that water used in laundry washing is drained through the second drainpipe 271.

The first drainpipe 171 for draining water used in the first washing unit 110 to the outside is connected to the second drainpipe 271 for draining water used in the second washing unit 210 so that overall water used in laundry washing can be drained to the outside. If necessary, the first drainpipe 171 is not connected to the second drainpipe 271 so that each of the first drainpipe 171 and the second drainpipe 281 may also drain water to the outside.

A dehydration unit 280 for dehydrating laundry contained in the second drum 230 may be installed in the second washing unit 210. In addition, the washing machine 100 according to the embodiment may include a reflector 111 a through which the user who is located outside of the first washing unit 110 can view laundry contained in the first washing unit 110.

The first washing unit 110 is located above the second washing unit 210, so that the user who desires to withdraw laundry from the drum may have difficulty in viewing the inside of the first washing unit 110. For this purpose, the reflector 111 a is provided at the first inlet 111 of the first washing unit 110, so that the user can easily view the inside of the first drum 130 through the reflector 111 a.

Assuming that the control panels 115 and 215 are arranged at the front surface of the washing machine 100 so as to control the washing machine 100, the first door 113 configured to open or close the first inlet 111 may be rotatable in the horizontal direction. The reflector 111 a is arranged at a rear side of the first opening 111, so that the user who stands adjacent to the control panels (115, 215) can view the inside of the first drum 130 through the reflector 111 a. In addition, the first washing unit 110 may include a laundry tray 105 on which laundry is placed.

The laundry tray 105 is contained in the first washing unit 110 so that laundry can be disposed thereon. The laundry tray 105 may be formed to be put into or withdrawn from the first washing unit 110.

However, the above-mentioned arrangement of the laundry tray 105 is not limited thereto, and the laundry tray of the embodiment is disposed in the second washing unit 210 so that the laundry tray can be put into or withdrawn from the second washing unit 210.

The laundry tray 105 may include a tray body 105 a on which laundry is placed; a handle unit 105 b extended from the tray body 105 a so that the user can grasp the handle unit 105 b; a sliding roller 105 c provided at a side of the tray body 105 a; and a sliding rail 105 d configured to guide operation of the sliding roller 105 c.

The laundry tray 105 may be movable to a first position and a second position. In more detail, the tray body 105 a is inserted into the first washing unit 110 at the first position. The laundry tray 105 moves to the second position from the first position so that laundry is placed on the tray body 105 a at the second position. Movement between the first position and the second position is achieved through the sliding roller 105 c and the sliding rail 105 d.

The scope or spirit of the laundry tray 105 is not limited to the above-mentioned shape, and any shape on which laundry can be placed can be applied to the laundry tray 105 without departing from the scope or spirit of the present invention.

FIG. 4 is a configuration view illustrating a vibration reduction unit of a washing machine according to an embodiment of the present invention.

Referring to FIG. 4, the vibration reduction unit 116 is installed between the first washing unit 110 and the second washing unit 210, and may be provided below the first washing unit 110.

An upper portion of the vibration reduction unit 116 may support a lower portion of the first washing unit 110, and a lower portion thereof may support an upper portion of the second washing unit 210.

The vibration reduction unit 116 may include an elastic unit 117 and a guide panel 118. The elastic unit 117 may include a support unit 117 a connected to the lower portion of the first washing unit 110, and an elastic member 117 b provided below the support unit 117 a to elastically support the support unit 117 a with respect to the top surface of the second washing unit 210.

The support unit 117 a is formed in a screw shape, and may be coupled to the lower portion of the first washing unit 110. The elastic member 117 b is coupled to a lower portion of the support unit 117 a so that the support unit 117 a and the first washing unit 110 can be elastically supported at the upper portion of the second washing unit 210.

Although the number or arrangement of the elastic unit 117 and elastic member 117 b is not limited thereto, for example, four elastic units including corresponding elastic members may be respectively arranged at individual vertexes at the lower portion of the first washing unit 110.

The guide panel 118 disposed between the first washing unit 110 and the second washing unit 210 may be formed along the circumference of the elastic unit 117. The first washing unit 110 and the second washing unit 210 may be spaced apart from each other due to the vibration reduction unit 116, and the guide panel 118 may be formed to enclose such spacing between the first and second washing units 110 and 210.

The guide panel 118 may be extended from the outer surface of the washing machine 100 in a manner that there is no step difference between the guide panel 118 and the washing machine 100.

Although the above-mentioned constituent elements of the vibration reduction unit 116 are merely examples for convenience of description, the scope or spirit of the present invention is not limited thereto, and any structure configured to reduce vibration generated from the first washing unit 110 from being applied to the second washing machine 210, and vice versa, can be applied to the vibration reduction unit 116 of the embodiment without departing from the scope or spirit of the present invention.

As described above, when the vibration reduction unit 116 is installed between the first washing unit 110 and the second washing unit 210 and the first and second washing units 110 and 210 are simultaneously driven (especially, when the first and second washing units perform a dehydration process), the first tub 120 of the first washing unit 110 and the second tub 220 of the second washing unit 20 may excessively vibrate at the same time.

In more detail, assuming that the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, if a resonance section (excessive vibration generated in an initial dehydration process) of the first washing unit 110 overlaps a resonance section of the second washing unit 210, overall structures of the washing machine 100 are abnormally vibrated by excessive vibration of the first tub 120 and the second tub 220, and there is a high risk of fluctuation in the washing machine 100.

In addition, if a normal section (abnormal vibration generated in the dehydration process) of the first washing unit 110 overlaps a normal section of the second washing unit 210, there is a high risk of increasing vibration of the washing machine 100 due to abnormal vibration of the first tub 120 and the second tub 220.

In order to address the above-mentioned issue, it is impossible to effectively reduce excessive vibration of the first tub 120 and the second tub 220 using a mechanical vibration reduction unit 116 disposed between the first washing unit 110 and the second washing unit 210.

In accordance with a method for controlling the washing machine according to the embodiment, the vibration sensor 300 is installed between the first washing unit 110 and the second washing unit 210, and persistently monitors vibration generated between the first washing unit 110 and the second washing unit 210, thereby reducing excessive vibration between the first tub 120 and the second tub 220.

The vibration sensor 300 is mounted to the vibration reduction unit 116 disposed between the first washing unit 110 and the second washing unit 210. In more detail, the vibration sensor 300 may be mounted to the guide panel 118 of the vibration reduction unit 116.

A vibration sensor 300 may employ a micro-electric mechanical system (MEMS) sensor measuring displacement of the first and second tubs 120 and 220 moving according to vibrations of the first and second tubs 120 and 220, a three-axis acceleration sensor measuring three-axes (X-direction, Y-direction, and Z-direction) vibrations of the first and second tubs 120 and 220, and a gyro sensor serving as an angular-velocity sensor. In this case, a displacement signal measured by the vibration sensor 300 may be generally used to estimate a balanced state of laundry contained in the first and second drums 130 and 230 during acceleration from low speed to high speed for reduction of vibration of the first and second tubs 120 and 220, so that the displacement signal can determine whether to perform a high-speed dehydration process on the basis of the estimation result.

Meanwhile, although the above-mentioned embodiment has exemplarily disclosed that the vibration sensor 300 is installed at the vibration reduction unit 116 disposed between the first washing unit 110 and the second washing unit 210 for convenience of description, the scope or spirit of the present invention is not limited thereto, and the vibration sensor 300 may be disposed between the first washing unit 110 and the second washing unit 210 in which the control panels 115 and 215 are respectively installed, or the vibration sensor 300 can be installed at any position where vibration of the first tub 120 and the second tub 220 can be detected in the dehydration process.

FIG. 5 is a block diagram illustrating a washing machine according to an embodiment of the present invention.

Referring to FIG. 5, the washing machine 100 includes a first washing unit 110 and a second washing unit 210. The washing machine 100 may further include a vibration sensor 300 installed between the first washing unit 110 and the second washing unit 210.

The vibration sensor 300 is an MEMS sensor installed between the first washing unit 110 and the second washing unit 210. The vibration sensor 300 may detect vibrations generated in the operation process of the first washing unit 110 and the second washing unit 210, and may transmit the detected vibrations to a first controller 410 and a second controller 510.

The first washing unit 110 may include a first input unit 400, a first controller 410, a first drive unit 420, and a first display unit 115 b.

The second washing unit 210 may include a second input unit 500, a second controller 510, a second drive unit 520, and a second display unit 215 b.

The first and second input units 400 and 500 may input commands to perform a washing process, a rinsing process, and a dehydration process of the first and second washing units 110 and 210 manipulated by a user, may be keys, buttons, switches, a touch pad, etc., and may include any device generating predetermined input data by pressing, touching, rotating, and the like.

In addition, the first and second input units 400 and 500 may include a plurality of buttons to input user commands (power on/off, reservation, washing, rinsing, dehydration, selected water level, etc.) related to operations of the first and second washing units 110 and 210. Among the plurality of buttons, there is a course selection button to select a washing course (such as a standard course, a wool course, a boiling course, etc.), according to laundry inserted into the first and second washing units 110 and 210.

In addition, the first and second input units 400 and 500 may be respectively provided at the first and second control panels 115 and 215, and may include a plurality of buttons 115 a and 215 a (e.g., power on/off, reservation, wash water temperature, soaking, washing, rinsing, dehydration, types of detergent, etc.) though which user commands related to operations of the first and second washing units 110 and 210 are input.

Each of the first and second controllers 410 and 510 is a microcomputer to control overall operations (such as washing, rinsing, dehydration, drying of laundry) of the first and second washing units 110 and 210 according to operation information received from the first and second input units 400 and 500. The first or second controller 410 or 510 sets a quantity of water for washing (target water level for washing) and for rinsing (target water level for rinsing), a target RPM and a motor operation rate (ON-OFF time of the washing motor), and time for washing and rinsing according to weight of laundry (load) in the selected washing course.

In addition, the first and second controllers 410 and 510 may persistently monitor vibrations generated between the first washing unit 110 and the second washing unit 210 using the vibration sensor 300, so that the first and second controllers 410 and 510 may control operations of the first washing unit 110 and the second washing unit 210 according to vibration states such as excessive vibration, normal vibration, and abnormal vibration.

A process in which excessive vibration, normal vibration, and abnormal vibration occur in the washing machine 100 may correspond to an exemplary case in which the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process.

Therefore, if the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, overall vibration of the washing machine 100 is detected using the vibration sensor 300, and specific information indicating whether the detected vibration data is excessive vibration data, normal vibration data, or abnormal vibration data is monitored, to determine if there is a need to control the operations of the first washing unit 110 and the second washing unit 210 according to the corresponding vibration state.

For this purpose, a method for actively controlling an excessive vibration state, a normal vibration state, and an abnormal vibration state of the washing machine 100 by controlling the first washing motor 150 for use in the first washing unit 110 installed at an upper part of the washing machine 100 according to excessive vibration, normal vibration, and abnormal vibration of the washing machine 100 will hereinafter be described in detail.

If the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, a method for actively controlling vibrations according to excessive vibration, normal vibration, and abnormal vibration of the washing machine 100 will hereinafter be described in detail.

If the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, the following three vibration conditions may be used, a detailed description of which will be given below.

(1) Vibration control method for an excessive vibration state of the washing machine 100.

The first washing unit 110 and the second washing unit 210 may start dehydration, excessive vibration (maximum vibration) of the first and second tubs 120 and 220 may occur when passing through the resonance points (i.e., rotation speeds (about 80 rpm) of the first and second washing motors to cause maximum vibration of the first and second tubs).

Excessive vibration (maximum vibration) displacement of the first and second tubs 120 and 220 occurs at a resonance point (about 100˜400 rpm) at which the rotation speed of the first and second washing motors 150 and 250 increases, so that the excessive vibration of the first and second tubs 120 and 220 may mainly occur when passing through the resonance point.

However, when the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, if an excessive section (about 100 to 400 rpm, see FIGS. 7 and 8) in which excessive vibration of the first washing unit 110 occurs overlaps an excessive section in which excessive vibration of the second washing unit 210 occurs, the excessive vibration of the first tub 120 and the excessive vibration of the second tub 220 are combined so that the overall washing machine 100 may abnormally vibrate.

Therefore, if vibration data detected by the vibration sensor 300 is higher in level than excessive vibration data (maximum vibration data generated when vibrations generated from the first and second washing units 110 and 210 passes through the resonance point at the initial dehydration process) when the first and second washing units 110 and 210 simultaneously perform the dehydration process, this means that excessive vibration has occurred at the beginning of the dehydration process, and the first controller 410 may delay a dehydration entry time of the first washing motor 150, so that the first washing unit 110 and the second washing unit 210 may differently control a passage time of the excessive resonance sections of the first and second washing units 110 and 210. Thereafter, after passing through the excessive vibration section of the second washing unit 210, the dehydration process of the first washing unit 110 starts operation.

(2) Vibration control method for a normal vibration state of the washing machine 100.

While the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, if vibration data detected by the vibration sensor 300 is higher in level than normal vibration data (i.e., data indicating whether RPM control is needed for the dehydration process), it is determined that excessive vibration higher than predetermined vibration has occurred in the normal section (vibration of about 700 rpm or higher, see FIGS. 7 and 8) of the dehydration process, and the first controller 410 may control the dehydration rpm of the first washing motor 150 to be lowered.

(3) Vibration control method for an abnormal vibration state of the washing machine 100.

If vibration data detected by the vibration sensor 300 is equal to or higher than abnormal vibration data (i.e., data indicating whether an unbalance error has occurred by unbalanced laundry during the dehydration process of 700 rpm or higher) when the first washing unit 110 and the second washing unit 210 simultaneously perform the dehydration process, it is determined that abnormal vibration has occurred in the normal section (about 700 rpm or higher, see FIGS. 7 and 8) of the dehydration process, and the first controller 410 may stop the first washing motor 150.

In addition, the first and second controllers 410 and 510 may store various setting information, usage information, and malfunction information. For example, the setting information may include control data for controlling the operations of the first and second washing units 110 and 210, reference data used for operation control of the washing machine 1, operation data generated when the first and second washing units 110 and 210 perform predetermined operations, and setup data entered by the first and second input units 400 and 500 in a manner that the first and second washing units 110 and 210 perform predetermined driving. For example, the usage information may include the number of specific operations executed by the first and second washing units 110 and 210, and model information of the first and second washing units 110 and 210. The malfunction information may include information regarding the cause of malfunction or information regarding the malfunctioned position on the condition that the first and second washing units 110 and 210 malfunction.

The first and second drive units 420 and 520 may drive the first and second washing motors 150 and 250 associated with the operations of the first and second washing units 110 and 210, a water supply valve 182, a drain motor 173, a drain pump 273, etc. according to the drive control signals of the first and second controllers 410 and 510.

The first and second display units 115 b and 215 b may display the operation states of the first and second washing units 110 and 210 and the user manipulation state according to display control signals of the first and second controllers 410 and 510.

In addition, if each of the first and second display units 115 b and 215 b is implemented as an LCD user interface (UI) capable of displaying text data, the LCD UI may display the operation states of the first and second washing units 110 and 210 so that the user can conduct proper actions in response to the displayed operation states.

If each of the first and second display units 115 b and 215 b is implemented as an LED UI, the user may recognize a malfunction state of the first and second washing units 110 and 210 using lighting or blinking and a difference in duration time.

The operation processes and effects of the washing machine having the first and second washing units 110 and 210 and a method for controlling the same according to the embodiments will hereinafter be described in detail.

FIG. 6A and FIG. 6B are a flowchart illustrating a control algorithm of a washing machine according to an embodiment of the present invention. FIG. 7 is a conceptual diagram illustrating a dehydration process profile of a washing machine according to an embodiment of the present invention. FIG. 8 is a graph illustrating a rotation speed of a washing motor and a vibration range of a tub for use in a washing machine according to an embodiment of the present invention.

FIG. 6A and FIG. 6B are a conceptual diagram of the algorithm for reducing vibration generated in the dehydration process during the washing process of the washing machine which classifies laundry into some kinds of laundry according to the capacity or categories of laundry and separately washes the classified laundry using a plurality of washing units 110 and 210 contained therein. A method for actively controlling an excessive vibration state, a normal vibration state, and an abnormal vibration state by controlling the first washing motor 150 of the first washing unit 110 installed above the washing machine 100 according to vibration states (excessive vibration, normal vibration, and abnormal vibration) of the washing machine 100 will hereinafter be described in detail.

In FIG. 6A and FIG. 6B, the user classifies laundry according to the capacity or categories of laundry, respectively puts the classified laundry into the first and second drum 130 and 230 of the first and second washing units 110 and 210, and selects a washing course and a washing function of each of the washing units 110 and 210 in operation 600. Thereafter, user-selected operation information is input to each of the first and second controllers 410 and 510 of the first and second washing units 110 and 210 through the first and second input units 400 and 500.

Besides, the user may manipulate the first and second input units 400 and 500, so that the user can select the washing course including the dehydration process according to laundry categories. In this case, the washing machine is designed to perform the dehydration process after completion of the dehydration process in association with the washing process.

Therefore, the first and second controllers 410 and 510 may start the washing processes of the first and second washing units 110 and 210 according to the washing course command entered by the first and second input units 400 and 500 in operation 602.

Subsequently, the first and second controllers 410 and 510 determine whether the first and second washing units 110 and 210 enter the dehydration process while performing the washing process according to the selected washing course in operation 604.

A reference for determining whether the first and second washing units 110 and 210 enter the dehydration process is as follows. If data detected by the vibration sensor 300 is equal to or higher than predetermined reference data (data generated when the first and second units simultaneously perform the dehydration process), it is determined that the first and second washing units 110 and 210 perform the dehydration process.

If the first and second washing units 110 and 210 simultaneously enter the dehydration process in operation 604, the first and second controllers 410 and 510 may drive the first and second washing motors 150 and 250 at a rotation speed (dehydration speed) determined according to the dehydration profile shown in FIG. 7 in operation 606.

The process for driving the first and second washing motors 150 and 250 accelerates the dehydration speed (rpm) along a predetermined slope ranging from the lowest speed (0 rpm) to the first highest speed (maximum rpm, about 900 rpm). If the dehydration speed reaches the first highest speed, the first highest speed is maintained for a predetermined time (about 200 seconds) and is then accelerated to a second highest speed (maximum rpm, about 1000 rpm) along a predetermined slope. Thereafter, if the resultant dehydration speed reaches the second maximum speed, the dehydration process is performed according to the dehydration profile for maintaining the second highest speed during a predetermined time (about 100 seconds) as shown in FIG. 7.

Assuming that the first and second washing motors 150 and 250 are simultaneously driven, if the excessive section in which the first washing unit 110 is excessively vibrated overlaps the excessive section in which the second washing unit 210 is excessively vibrated, or if abnormal vibration occurs in the normal section, there is a high risk of fluctuation in the washing machine 100 or frame vibration of the washing unit may increase.

In order to address the above-mentioned issues, the vibration sensor 300 detects vibrations of the first tub 120 and the second tub 220 when the first and second washing motors 150 and 250 are simultaneously driven, so that the detected vibrations are applied to the first controller 410 in operation 608. As unbalanced vibration detected by the vibration sensor 300 increases, the magnitude of eccentricity caused by unbalanced laundry also increases.

Therefore, the first controller 410 may compare eccentricity data detected by the vibration sensor 300 with predetermined excessive vibration data (i.e., maximum vibration data generated when passing through the resonance point at an initial stage of the dehydration process), and thus determine whether the detected data is equal to or higher than excessive vibration data in operation 610.

If the detected data is equal to or higher than excessive vibration data in operation 610, the first controller 410 determines the occurrence of excessive vibration when entering the dehydration process, and then delays the operation for controlling the first washing motor 150 to enter the dehydration process in operation 612. Assuming that the first and second washing units 110 and 210 are simultaneously driven, if there occurs overlapping of an excessive section (about 100˜400 rpm, see FIGS. 7 and 8) in which the first and second tubs 120 and 220 are excessively vibrated, the overall washing machine 100 is abnormally vibrated, the dehydration entry time of the first washing motor 150 is delayed and the passing times of the excessive vibration sections of the first and second washing units 110 and 210 are differently controlled, so that the danger of fluctuation of the washing machine 100 is prevented. Therefore, the first controller 410 controls the second washing unit 210 to pass through the excessive vibration section and then controls the first washing unit 110 to start the dehydration process.

Subsequently, the first and second controllers 410 and 510 determine whether the dehydration process is completed in operation 614. If the dehydration process is not completed, the first and second controllers 410 and 510 feed back to the operation 606, and the first and second washing motors 150 and 250 are driven at predetermined rotation speeds according to the dehydration profile.

If the detected data is not higher than the excessive vibration data in operation 610, the first controller 410 may compare eccentricity data detected by the vibration sensor 300 with predetermined normal vibration data (i.e., data used to determine whether rpm control is required for the dehydration process) so as to determine whether the detected data is equal to or higher than normal vibration data in operation 620.

In operation 620, if the detected data is equal to or higher than normal vibration data, the first controller 410 determines the occurrence of predetermined vibration or greater in a normal section (about 700 rpm or higher, see FIGS. 7 and 8) of the dehydration process, and controls reduction of the dehydration rpm of the first washing motor 150 in operation 622. Assuming that the first washing unit 110 and the second washing unit 210 are simultaneously driven, if the degree of vibrations generated from the first tub 120 and the second tub 220 is equal to or greater than predetermined vibration, the degree of vibrations of the washing machine 100 increases. In order to prevent increase in vibration of the washing machine 100, a dehydration speed of the first washing motor 150 is reduced, so that the dehydration speed of the washing machine 100 can also be reduced. Thereafter, the first controller 410 reduces the dehydration rpm of the first washing motor 150, and proceeds to operation 614 so that subsequent operations after operation 614 are then performed.

If the detected data does not indicate the occurrence of abnormal vibration data in operation 620, the first controller 410 may compares eccentricity data detected by the vibration sensor 300 with predetermined abnormal vibration data (i.e., data indicating whether unbalance errors occur in the normal section of the dehydration process due to unbalanced laundry), and thus determines whether the detected data is equal to or higher than abnormal vibration data in operation 630.

If the detected data is equal to or higher than abnormal vibration data in operation 630, the first controller 410 determines the occurrence of abnormal vibration in the normal section (about 700 rpm or higher, see FIGS. 7 and 8) of the dehydration process, the first washing motor 150 stops operation in operation 632. Assuming that the first washing unit 110 and the second washing unit 210 are simultaneously driven, if abnormal vibrations of the first tub 120 and the second tub 220 occur, this means that an unbalance error caused by unbalanced laundry has occurred, so that the first washing motor 150 stops to prevent frame vibration of the washing machine 100 from increasing.

Meanwhile, although the above embodiments have exemplarily disclosed a method for actively controlling excessive vibration, normal vibration, and abnormal vibration of the washing machine 100 by allowing the first washing unit 110 installed above the washing machine 100 to control RPM of the dehydration process according to vibration states (e.g., excessive vibration, normal vibration, and abnormal vibration) of the washing machine 100, the scope or spirit of the present invention is not limited thereto, it should be noted that excessive vibration, normal vibration, and abnormal vibration of the washing machine 100 can also be actively controlled by allowing the second washing unit 210 installed below the washing machine 100 to control RPM of the dehydration process according to vibration states (e.g., excessive vibration, normal vibration, and abnormal vibration) of the washing machine 100.

As is apparent from the above description, according to the washing machine and the method for controlling the same, several washing units capable of classifying laundry according to the capacity or categories of laundries so as to separately wash the classified laundry in different washing ways are installed at upper and lower parts of the washing machine, so that a user need not manually select some laundry to be separately washed from among overall laundry and the washing machine need not be driven several times, resulting in reduction of an overall washing time and implementation of energy saving.

In addition, if several washing units are simultaneously driven, the washing machine according to the embodiments persistently monitors vibrations generated between the several washing units using a vibration sensor installed between the several washing units, so that excessive or abnormal vibrations of the washing machine can be effectively reduced.

The above-mentioned embodiments are disclosed only for illustrative purposes. The above-mentioned disclosures are used only to indicate the embodiments, and the present invention can also be used in various combinations, modifications and environments without departing from the scope or spirit of the present invention. That is, the present invention can be readily modified or changed within the scope of the present invention, within the scope equivalent to the disclosed content, and/or within the scope of technology or knowledge well known to those skilled in the art. The above-mentioned embodiments have exemplarily described the best mode for implementing a technical idea of the present invention, and various modifications needed for detailed application fields and utilities can also be made available. Therefore, the above-mentioned embodiments are exemplary and explanatory and are not intended to limit the scope of the present invention. In addition, the appended claims may conceptually include other embodiments or examples without departing from the scope or spirit of the present invention as necessary.

Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

What is claimed is:
 1. A washing machine, comprising: a plurality of washing units; a vibration sensor configured to detect vibrations of the plurality of washing units; and a controller, while the plurality of washing units are in a dehydration process, configured to control the dehydration process of any one of the plurality of washing units according to data of the vibrations detected by the vibration sensor.
 2. The washing machine according to claim 1, further comprising: a plurality of tubs installed in the plurality of washing units, respectively; a plurality of drums rotatably installed in the plurality of tubs, respectively; and a plurality of motors configured to respectively rotate the plurality of drums, wherein the controller controls any one of the plurality of motors using the data of the vibrations detected by the vibration sensor.
 3. The washing machine according to claim 2, wherein the controller compares the data of the vibrations detected by the vibration sensor with excessive vibration data, and delays dehydration entry of any one of the plurality of motors while the detected data is equal to or higher than the excessive vibration data, resulting in reduction of vibrations of the washing machine.
 4. The washing machine according to claim 3, wherein the excessive vibration occurs in an entry section of the dehydration process.
 5. The washing machine according to claim 2, wherein the controller compares the data of the vibrations detected by the vibration sensor with normal vibration data, and controls a dehydration RPM of any one of the plurality of motors while the detected data is equal to or higher than the normal vibration data, resulting in reduction of vibrations of the washing machine.
 6. The washing machine according to claim 2, wherein the controller compares the data of the vibrations detected by the vibration sensor with abnormal vibration data, and stops any one of the plurality of motors while the detected data is equal to or higher than the abnormal vibration data, resulting in reduction of vibrations of the washing machine.
 7. The washing machine according to claim 6, wherein the abnormal vibration occurs in a normal progressing section of the dehydration process.
 8. The washing machine according to claim 2, wherein the plurality of washing units includes: a first washing unit having a first tub, a first drum, and a first inlet, the first inlet being arranged at an upper part of the first washing unit so as to enable loading and unloading of laundry; and a second washing having a second tub, a second drum and a second inlet, the second inlet being arranged at a front surface of the second washing machine so as to enable loading and unloading of laundry.
 9. The washing machine according to claim 8, wherein the vibration sensor is configured to detect vibrations generated between the first washing unit and the second washing unit while the plurality of motors is simultaneously rotated at a high speed.
 10. The washing machine according to claim 8, wherein the vibration sensor is installed between the first washing unit and the second washing unit, the vibration sensor measures displacement of the first tub and the second tub moving in response to rotation of the first drum and the second drum, and transmits the measured displacement to the controller.
 11. The washing machine according to claim 8, further comprising: a vibration reduction unit installed between the first washing unit and the second washing unit, configured to include at least one elastic unit so as to reduce vibration of the washing machine.
 12. The washing machine according to claim 11, wherein the vibration sensor is mounted to the vibration reduction unit.
 13. The washing machine according to claim 1, wherein the plurality of washing units includes: a first washing unit and a second washing unit vertically stacked to be operated independently of each other.
 14. The washing machine according to claim 13, wherein the first washing unit and the second washing unit have different capacities.
 15. The washing machine according to claim 13, wherein the first washing unit and the second washing unit are comprised of a drum washing machine or a fully automatic washing machine.
 16. A washing machine, comprising: a plurality of washing units configured to form an external appearance of the washing machine; a plurality of tubs installed in the plurality of washing units, respectively; a plurality of drums rotatably installed in the plurality of tubs, respectively; a plurality of motors configured to respectively rotate the plurality of drums; a vibration sensor configured to detect vibrations of the plurality of tubs during rotation of the plurality of drums; and a controller configured to control any one of the plurality of motors according to data of the vibrations detected by the vibration sensor so as to reduce vibration of the washing machine.
 17. The washing machine according to claim 16, wherein the plurality of washing units includes: a first washing unit having a first tub, a first drum, and a first inlet, the first inlet being arranged at an upper part of the first washing unit so as to enable loading and unloading of laundry; and a second washing unit having a second tub, a second drum, and a second inlet, the second inlet being arranged at a front surface second washing unit so as to enable loading and unloading of laundry.
 18. The washing machine according to claim 17, wherein the vibration sensor is installed between the first washing unit and the second washing unit, and detects vibrations generated between the first washing unit and the second washing unit while the plurality of motors is simultaneously rotated at a high speed.
 19. The washing machine according to claim 18, further comprising: a vibration reduction unit installed between the first washing unit and the second washing unit, configured to include at least one elastic unit so as to reduce vibration of the washing machine.
 20. The washing machine according to claim 19, wherein the vibration sensor is mounted to the vibration reduction unit.
 21. A method for controlling a washing machine having a plurality of washing units, comprising: determining whether the plurality of washing units are in a dehydration process; detecting vibrations of the plurality of washing units using a vibration sensor, while the plurality of washing units are determined to be in the dehydration process; and controlling the dehydration process of any one of the plurality of washing units according to data of the detected vibrations.
 22. The method according to claim 21, wherein the determining includes: determining that the plurality of washing units simultaneously perform the dehydration process while the detected data is equal to or higher than reference data.
 23. The method according to claim 21, wherein the controlling includes: controlling any one of the plurality of motors configured to rotate the plurality of drums respectively installed in the plurality of washing units, and thus reducing vibration of the washing machine.
 24. The method according to claim 23, further comprising: comparing the data of the vibrations detected by the vibration sensor with excessive vibration data; and delaying dehydration entry of any one of the plurality of motors while the detected data is equal to or higher than the excessive vibration data, and thus reducing vibration of the washing machine.
 25. The method according to claim 23, further comprising: comparing the data of the vibrations detected by the vibration sensor with normal vibration data; and controlling a dehydration RPM of any one of the plurality of motors while the detected data is equal to or higher than the normal vibration data, and thus reducing vibration of the washing machine.
 26. The method according to claim 23, further comprising: comparing the data of the vibrations detected by the vibration sensor with abnormal vibration data; stopping operation of any one of the plurality of motors while the detected data is equal to or higher than the abnormal vibration data, and thus reducing vibration of the washing machine.
 27. The method according to claim 23, wherein the detecting includes: detecting, by a vibration sensor disposed between the plurality of washing units, vibrations of the washing machine during rotation of the plurality of drums.
 28. The method according to claim 23, wherein the detecting includes: detecting, by a vibration sensor disposed between the plurality of washing units, vibrations generated between the plurality of washing units during high-speed rotation of the plurality of motors. 